HELP !!!!!
I need some advice on a voltage converter/ regulator that I have been
building.
For some reason no one makes a commercially available regulator that boosts
12v up to 28V so that one can operate a 28volt aircraft device on a 12v
Europa system.
---From time to time there have been published circuits on this forum for such
a device and I have eventually got around to attempting to build one. The
circuit is constructed around a LM2577 step up voltage Integrated circuit.
By changing the component values the output voltage can be changed. The same
circuit is published on P235 of the latest Maplin catalog.
Anyway my problem is this. Having assembled the circuit I tested it on the
workbench and it works fine giving 27.8 volts across a 50 ohm dummy load.
The trouble is that as soon as it is placed in a metal case the voltage
immediately drops down to 13V.
Losing the case is not really an option as it will probably affect the other
instruments and anyway even the proximity of a flat metal sheet (eg a radio
case) has the same effect. We tried grounding the case but it didnt work.
Anyone in the know have any suggestions.
Carl Pattinson
|